Adapt calls and referendum submission to the post-AHM world

[seadanda]

Also use metadata path instead of insecure url and use xcm v5

Manually verified working with fellows release v1.9.2 on Kusama and v2.0.1 and later on both Kusama and Polkadot.

TODO:

• [x] --additional is ~~currently broken for at least Polkadot~~ fixed
• [x] fix tests: hardcoded calls need to be manually mapped from Kusama to Kusama Asset Hub
• [x] likewise for Polkadot
• [x] use dev.papi.how links
• [x] add light client support